A conventional power-assisted steering system of a bus or a truck is a hydraulic power steering (HPS) system. The conventional power-assisted steering system includes a hydraulic pump driven by a motor or an engine of a vehicle to provide an assisting steering power, thereby allowing the conventional power-assisted steering system to perform the power-assisted steering function. In order for the vehicle to embody intelligent functions, such as automatic driving system, and to overcome drawbacks of the abovementioned conventional power-assisted steering system, such as low energy efficiency and inability to steer the vehicle automatically, a product which combines an electric power steering (EPS) system and a hydraulic steering gear is widely applied in heavy trucks.
Conventional buses can be classified into three types according to weight: full-size buses, midibuses, and minibuses. A full-size bus usually has a long front overhang, a minibus usually has a short front overhang, and a midibus may either have a long front overhang or a short front overhang. The EPS system may replace the HPS system completely and be equipped in the midibuses and the minibuses so as to embody the intelligent functions and decrease costs of manufacturing and maintaining.
For the full-size bus having a long front overhang, a gearbox with a bevel gear set is connected to a steering column, and transfers the rotational motion of a steering wheel through an intermediate shaft to a steering gear mounted behind the steering column to steer the vehicle.
For the vehicle having a short front overhang, a steering gear is mounted below a steering column and is directly connected to the steering column. The rotational motion of a steering wheel is transferred directly to the steering gear to steer the vehicle.
According to the above description, different types of vehicles may have different ways of connection between the steering column and the steering gear with different elements linked therebetween, thereby resulting in a complicated manufacturing process and a relatively high cost.